Backwards compatible, extended method to execute check number calculation of IMEI

• US 7,054,657 B2
• Filed: 02/15/2001
• Issued: 05/30/2006
• Est. Priority Date: 02/17/2000
• Status: Expired due to Fees

• Current Assignee: Nokia Mobile Phones UK Limited (Nokia Corporation)
• Original Assignee: Nokia Corporation
• Inventors: Alanärä, Seppo
• Primary Examiner(s): Tran, Pablo N.
• Application Number:
  US09/783,917
• Publication Number:
  US 20010027117A1
• Time in Patent Office: 1,930 Days
• Field of Search: 455/551, 455/550, 455410-411, 455/414, 455/80.3, 455/75.1, 455/435, 455/925, 455/550.1, 455/432.2, 455/432.3, 455/433, 455/434, 455/435.1, 455/461, 455/414.1, 455/414.4, 455/439, 455/429, 380/281, 380/182, 380/277, 380/255, 713/168, 713/200, 713/182
• US Class Current: 455/551
• CPC Class Codes: H04W 8/22 Processing or transfer of terminal data, e.g. status or physical capabilities
• CPC Class Codes: H04W 8/26 Network addressing or numbering for mobility support

Abstract

A method is taught to provide an improved mobile station International Mobile Equipment Identity (IMEI) code having at least a six digit hexadecimal SNR representation, in conjunction with modifying a Check Digit calculation procedure so as to insure backwards compatibility with an existing installed base of mobile stations having a six digit BCD SNR representation.

Claims

1. A method for use with a mobile station of a type that stores a 14 digit International Mobile Equipment Identity (IMEI) code for generating a Check Digit (CD), comprising steps of:

executing a preliminary step of encoding the 14 digit (D1, D2, D3, . . . , D14) IMEI in a hexadecimal representation;

then computing the CD by,

(A) doubling the values of the odd digits (D1, D3, D5, . . . , D13) of the IMEI using the hexadecimal number base;

(B) adding together the individual digits of the seven numbers obtained in Step A, and adding this sum to the sum of all of the even labeled digits (D2, D4, D6, . . . D14) of the IMEI using the hexadecimal number base; and

(C) if the number obtained at the end of Step B ends in zero (0), setting the CD to zero (0), else if the number obtained at the end of Step B does not end in zero (0), setting the CD to be the difference between that number subtracted from the next highest hexadecimal number which does end in zero (0).

2. A method for use by a wireless communication system that includes a network and a plurality of mobile stations that each store a 14 digit International Mobile Equipment Identity (IMEI) code, the method generating a Check Digit (CD) and comprising steps of:

for a first type of mobile stations, executing a preliminary step of encoding the 14 digit (D1, D2, D3, . . . , D14) IMEI in a binary coded decimal (BCD) representation;

for a second type of mobile stations, executing a preliminary step of encoding the 14 digit (D1, D2, D3, . . . , D14) IMEI in a hexadecimal representation,

then computing the CD in the network, regardless of whether an IMEI is received from the first type of mobile station or from the second type of mobile station, by performing the steps of,

(A) doubling the values of the odd digits (D1, D3, D5, . . . , D13) of the IMEI using the hexadecimal number base;

(B) adding together the individual digits of the seven numbers obtained in Step A, and adding this sum to the sum of all of the even labeled digits (D2, D4, D6, . . . , D14) of the IMEI using the hexadecimal number base; and

(C) if the number obtained at the end of Step B ends in zero (0), setting the CD to zero (0), else if the number obtained at the end of Step B does not end in zero (0), setting the CD to be the difference between that number subtracted from the next highest hexadecimal number which does end in zero (0).